1. Field of the Invention
The present invention relates to an apparatus for remedying polluted soil material and polluted soil and an efficient method of remedying polluted soil material and polluted soil using the same. The present invention relates to a polluted gas-purifying apparatus and a method of purifying the same, too.
2. Related Background Art
Recently, as measures to solve environmental pollution problems, various attempts have been made to remove pollutants from soil polluted with organic substances or the like to remedy soil, and for example, a method in which pollutants in soil are aspirated using a vacuum pump and treated with activated carbon, bioremediation utilizing degradation activities of microorganisms, a method for decomposing a pollutant by irradiating the soil with UV have been proposed.
The vacuum aspiration method cannot always be said an efficient method, since pollutants are removed by adsorption to activated carbon which has insufficient efficiency, it is difficult to treat materials having a large water content, and retreatment of used activated carbon that has adsorbed pollutants is a problem.
As for the bioremediation, the expression of degradation activities and the proliferation process of microorganisms are not always stable and degradation process management is sometimes relatively difficult. Thus, the bioremediation has rarely been in the actual use to cope with soil pollution, especially with organic chlorinated compounds.
An apparatus for degrading a pollutant by means of light is known, which is a photodegradation apparatus utilizing a phenomenon that ultraviolet of UV-B, C degrades some kinds of pollutants. Japanese Patent Application Laid-Open Nos. 09-299753 and 10-180040 disclose such apparatus.
It is an object of the present invention to provide an apparatus that can efficiently treat polluted soil using chlorine-containing water, excluding the necessity of treatment with activated carbon or microorganisms and without a risk of secondary pollution, and an efficient method of remedying polluted soil using the apparatus. It is also an object of the present invention to provide a summary polluted gas-purifying apparatus and a purifying method using the apparatus.
A remediation apparatus of the present invention to achieve the above described object is a polluted soil remediation apparatus comprising a treatment tank in which a pollutant degradable with light irradiation in the presence of chlorine is extracted as a gas containing the pollutant from a polluted soil and a mixed gas of the gas containing the pollutant and a chlorine-containing gas is irradiated with light to degrade the pollutant, wherein the apparatus comprises:
an aspirating means of aspirating the gas containing the pollutant from the polluted soil;
a chlorine-containing gas generation means of generating the chlorine-containing gas;
a mixing means of mixing the gas containing the pollutant extracted by the aspirating means and the chorine-containing gas generated by the chlorine-containing gas generation means to form the mixed gas;
a treatment region where the mixed gas is introduced; and
a light irradiation means of irradiating the treatment region with light to degrade the pollutant contained in the mixed gas; and
an exhaust means of exhausting a degradation-treated gas from the treatment region of the treatment tank.
A combination of a pit provided in the polluted soil and a vacuum pump for aspirating the gas containing the pollutant through the pit can be used suitably as the aspirating means in the polluted soil remediation apparatus.
Means bringing a functional water, which is capable of generating an air containing chlorine by being aired, into contact with air as well as a chlorine cylinder can be used suitably as the means of generating the chlorine-containing gas. Concretely speaking, a means of sending air to a surface of the functional water, a means of bringing small droplets of the functional water into contact with air, e.g. a nozzle as a means of ejecting the functional water, and a means of aerating the functional water with air can be suitably used.
Means comprised of a water tank, a means of generating the functional water, a means of introducing air into the water tank, a means of discharging the generated chlorine-containing gas and a means of discharging the functional water after being used for the generation of the chlorine-containing gas can be also suitably used as the means of generating the choline-containing gas.
The method of remedying polluted soil of the present invention is a polluted soil remediation method wherein a pollutant degradable with light irradiation in the presence of chlorine is extracted as a gas containing the pollutant from a polluted soil and a mixed gas of the gas containing the pollutant and a chlorine-containing gas is irradiated with light to degrade the pollutant, which comprises the steps of:
aspirating the gas containing the pollutant from the polluted soil;
introducing the chlorine-containing gas;
mixing the gas containing the pollutant and the chlorine-containing gas to form the mixed gas;
irradiating the mixed gas introduced in a treatment region of a treatment tank with light to degrade the pollutant contained in the mixed gas; and
exhausting the degradation-treated mixed gas from the treatment region.
For the step of aspirating the pollutant-containing gas from a polluted soil, it is preferable to use the pit formed in the polluted soil and the vacuum pump for aspirating the pollutant-containing gas through the pit.
It is suitably used in the method of introducing the chlorine-containing air to bring the functional water into contact with air as well as a chlorine cylinder. Concretely speaking, a step of sending air to a surface of the functional water, a step of bring small droplets of the functional water into contact with air, e.g. a step of ejecting the functional water by a nozzle, and a step of aerating the functional water with air can be suitably used.
The step of generating the chlorine-containing air may comprise the steps of: generating chlorine-containing water; supplying the chlorine-containing water to a water tank; introducing air to the water tank; exhausting the generated chlorine-containing air; and draining the chlorine-containing water used for generation of the chlorine-containing air.
The step of generating the chlorine-containing water to be supplied to the water tank may comprise the steps of: supplying electrolyte-containing water to the water tank; and applying a potential to the electrolyte-containing water in the water tank.
According to the present invention, for example, first, air containing pollutants in a shaft is aspirated by a vacuum pump or the like. Then, chlorine-containing water is exposed to air to generate chlorine-containing air. The chlorine-containing air is mixed with the air containing the pollutants in a treatment tank and a mixture is irradiated with light. The pollutants are degraded by light irradiation, and then a liquid component and air are discharged. Thus, organic components such as trichloroethylene, which has become an issue as a harmful substance, can be efficiently extracted from soil and treated for degradation.
According to still another aspect of the present invention, there is provided a pollutant degrading apparatus comprising a bag-shaped treatment tank a shape and a capacity of which are variable, in which tank a mixed gas of a gas containing a pollutant degradable with light irradiation in the presence of chlorine and a chlorine-containing gas is irradiated with light to degrade the pollutant, wherein the apparatus comprises:
a chlorine-containing gas generation means of generating chlorine in a gas;
a mixing means of mixing the gas containing the pollutant and the chorine-containing gas generated by the chlorine-containing gas generation means to form the mixed gas;
a treatment region where the mixed gas is introduced;
a light irradiation means of irradiating the treatment region with light to degrade the pollutant contained in the mixed gas; and
an exhaust means of exhausting the degradation-treated gas from the treatment region of the treatment tank.
According to a further aspect of the present invention, there is provided a pollutant-degrading method in which a mixed gas of a gas containing a pollutant degradable with light irradiation in the presence of chlorine and a chlorine-containing gas is irradiated with light to degrade the pollutant, which comprises the steps of:
introducing the chlorine-containing gas;
mixing the gas containing the pollutant and the chlorine-containing gas to form the mixed gas;
irradiating the mixed gas introduced in a treatment region of a bag-shaped treatment tank a shape and a capacity of which are variable with light to degrade the pollutant contained in the mixed gas; and
exhausting the degradation-treated mixed gas from the treatment region.
For the bag-shaped treatment tank a shape and a capacity of which are variable used in the above-mentioned present inventions, it is preferable to have an accordion-fold structure. Further, it is preferable to have a case covering the bag-shaped treatment tank. It is more preferable to locate the light irradiation means in a region inside the case and outside the bag-shaped treatment tank.
It is preferable that the gas containing said pollutant to be treated is at least one selected from the group consisting of a polluted exhaust gas, a polluted gas desorbed from an activated carbon and a polluted gas originating from an aeration of a polluted water as well as a gas aspirated from a polluted soil.
According to the polluted soil remediation method using the polluted soil remediation apparatus, polluted soil can be efficiently treated on site without the necessity of treatment with activated carbon, a problem of secondary pollution, or the necessity of activity control management resulted from the use of microorganisms. Excavated soil can also be cleaned.
It is possible to utilize a tank the shape and capacity of which are variable as the treatment tank for the present invention. Such a tank brings about the following advantageous effects:
(1) saving cost of the apparatus,
(2) facilitating the installation of the apparatus and improving the mobility/removability thereof because of the light weight of the tank,
(3) facilitating the folding of the tank because of the accordion-fold structure, and
(4) altering easily the size of the tank according to the degrading condition because of the accordion-fold structure and bag shape of the tank, whereby the retention time (reaction time) can be optimized in accordance with the situation.
Further the bag-shaped treatment tank regarding the present invention can be applied to the degrading treatments of a polluted exhaust gas, a polluted gas desorbed from an activated carbon and a polluted gas originating from an aeration of a polluted water as well as a gas aspirated from a polluted soil.